Search Publications
The Short-term Stability of a Simulated Differential Astrometric Reference Frame in the Gaia Era
Sozzetti, Alessandro; Abbas, Ummi; Bucciarelli, Beatrice +5 more
We use methods of differential astrometry to construct a small field inertial reference frame stable at the micro-arcsecond level. Such a high level of astrometric precision can be expected with the end-of-mission standard errors to be achieved with the Gaia space satellite using global astrometry. We harness Gaia measurements of field angles and …
Heights of Coronal Mass Ejections and Shocks Inferred from Metric and DH Type II Radio Bursts
Shanmugaraju, A.; Suresh, K.; Lee, Jae-Ok +2 more
A set of 27 continuous events that showed extension of metric Type-II radio bursts (m-Type IIs) into the deca-hectometric (DH) domain is considered. The coronal mass ejections (CMEs) associated with this type of continuous event supply more energy to produce space-weather effects than the CMEs that produce Type-II bursts in any one region. Since t…
Rosetta Mission: Electron Scattering Cross Sections—Data Needs and Coverage in BEAMDB Database
Mason, Nigel J.; Jevremović, Darko; Bredehöft, Jan Hendrik +2 more
The emission of [O I] lines in the coma of Comet 67P/Churyumov-Gerasimenko during the Rosetta mission have been explained by electron impact dissociation of water rather than the process of photodissociation. This is the direct evidence for the role of electron induced processing has been seen on such a body. Analysis of other emission features is…
Galactic Latitude Dependence of Near-infrared Diffuse Galactic Light: Thermal Emission or Scattered Light?
Matsuura, S.; Sano, K.
Near-infrared (IR) diffuse Galactic light (DGL) consists of scattered light and thermal emission from interstellar dust grains illuminated by the interstellar radiation field (ISRF). At 1.25 and 2.2 µ {{m}}, a recent observational study shows that intensity ratios of the DGL to interstellar 100 µ {{m}} dust emission steeply decrease to…
DDO 161 and UGCA 319: an isolated pair of nearby dwarf galaxies
Rizzi, L.; Karachentsev, I. D.; Makarova, L. N. +3 more
We report Hubble Space Telescope/Advanced Camera for Surveys observations of two nearby gas-rich dwarf galaxies: DDO 161 and UGCA 319. Their distances determined via the tip of the red giant branch are 6.03_{-0.21}^{+0.29} and 5.75 ± 0.18 Mpc, respectively. The galaxies form an isolated pair dynamically well separated from the nearest neighbours: …
Do water fountain jets really indicate the onset of the morphological metamorphosis of circumstellar envelopes?
Hsia, Chih-Hao; Yung, Bosco H. K.; Nakashima, Jun-ichi +1 more
Small-scale bipolar jets with short dynamical ages from 'water-fountain' (WF) sources are regarded as an indication of the onset of circumstellar envelope morphological metamorphosis of intermediate-mass stars. Such a process usually happens at the end of the asymptotic giant branch (AGB) phase. However, recent studies found that WFs could be AGB …
Hard X-Ray/Soft Gamma-Ray Experiments and Missions: Overview and Prospects
Frontera, Filippo; Cavallari, Erica
Starting from 1960s, a great number of missions and experiments have been performed for the study of the high-energy sky. This review gives a wide vision of the most important space missions and balloon experiments that have operated in the 10-600 keV band, a crucial window for the study of the most energetic and violent phenomena in the Universe.…
Updating the orbital ephemeris of the dipping source XB 1254-690 and the distance to the source
Pintore, Fabio; Sanna, Andrea; Gambino, Angelo F. +5 more
XB 1254-690 is a dipping low mass X-ray binary system hosting a neutron star and showing type I X-ray bursts. We aim at obtaining a more accurate orbital ephemeris and at constraining the orbital period derivative of the system for the first time. In addition, we want to better constrain the distance to the source in order to locate the system in …
Thermal gravitational-wave background in the general pre-inflationary scenario
Xia, Jun-Qing; Wang, Kai; Santos, Larissa +1 more
We investigate the primordial gravitational waves (PGWs) in the general scenario where the inflation is preceded by a pre-inflationary stage with the effective equation of state w. Comparing with the results in the usual inflationary models, the power spectrum of PGWs is modified in two aspects: one is the mixture of the perturbation modes caused …
New ATCA, ALMA and VISIR observations of the candidate LBV SK -67 266 (S61): the nebular mass from modelling 3D density distributions
Paladini, R.; Umana, G.; Agliozzo, C. +10 more
We present new observations of the nebula around the Magellanic candidate Luminous Blue Variable S61. These comprise high-resolution data acquired with the Australia Telescope Compact Array (ATCA), the Atacama Large Millimetre/Submillimetre Array (ALMA), and the VLT Imager and Spectrometer for mid Infrared (VISIR) at the Very Large Telescope. The …